A light source device described in Patent Literature 1 includes three prism-type polarization beam splitters that generate luminous flux having three wavelength regions of red, green, and blue, guide the luminous flux to a reflective-type liquid-crystal panel, obtain image lights having the three wavelength regions respectively, composite the image lights, and output the image lights. For example, considering an accuracy of an arrangement of prisms in a manufacturing process, each of the polarization beam splitters is structured by a combination of the prisms having different heights (For example, see paragraphs [0026] and [0028] of the specification, and FIGS. 6 and 7 of Patent Literature 1.).
A polarization beam splitter described in Patent Literature 2 is structured in order that each attached surface of two right-angle prisms has a different area from each other. According to the structure, a part of the attached surface of the one right-angle prism functions as a reference plane when the polarization beam splitter is attached to an attachment member (For example, see paragraph [0015] of the specification and FIG. 1 of Patent Literature 2.).